Ionic liquids for agricultural residue removal

Abstract

A method of reducing the proportion of agricultural residues (ARs), such as pesticides and herbicides, present in an essential oil, comprising the treatment of the oil with an ionic liquid that has at most limited solubility in the oil, the ionic liquid having an anion and a cation chosen from the following table: cation anion dialkylimidazolium alkylsulfate trialkylimidazolium dicyanamide dialkylpyridinium alkylsulfonate dialkylpyrrolidinium alkylphosphate thiocyanate fluoroacetate fluoroalkyl sulfonate tetrafluoroborate halide The method is particularly effect with citrus oils, especially orange oil, and it can remove most ARs, without removing essential components of the oil.

The invention claimed is: 
     
       1. A method of reducing the proportion of agricultural residues present in an essential oil, comprising treatment of the oil with an ionic liquid that has at most limited solubility in the oil, the ionic liquid having an anion and a cation chosen from the following table: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   cation 
                   anion 
                 
                     
                     
                 
                     
                   dialkylimidazolium 
                   alkylsulfate 
                 
                     
                   trialkylimidazolium  
                   dicyanamide 
                 
                     
                   dialkylpyridinium 
                   alkylsulfonate 
                 
                     
                   dialkylpyrrolidinium 
                   alkylphosphate 
                 
                     
                     
                   thiocyanate 
                 
                     
                     
                   fluoroacetate 
                 
                     
                     
                   fluoroalkyl sulfonate 
                 
                     
                     
                   tetrafluoroborate 
                 
                     
                     
                   halide. 
                 
                     
                     
                 
             
                
                
                
               
               
                
                
                
                
                
                
                
                
                
                
               
            
           
         
       
     
     
       2. The method according to  claim 1 , in which the ionic liquid is at least one of the following:
 1-Butyl-2,3-dimethylimidazolium (trialkylimidazolium) tetrafluoroborate, 
 1-Butyl-3-methylimidazolium (dialkylimidazolium) dicyanamide, 
 1-Hexyl-3-methylimidazolium (dialkylimidazolium) chloride, 
 3-Methyl-1-octylimidazolium (dialkylimidazolium) chloride, 
 1-Butyl-3-methylimidazolium methylsulfate, 
 N-Butyl-3-methylpyridinium dicyanamide, 
 1-Butyl-1-methylpyrrolidinium dicyanamide, 
 4-Methyl-N-butylpyridinium tetrafluoroborate, 
 1-Ethyl-3-methylimidazolium (dialkylimidazolium) dicyanamide, 
 1-Ethyl-3-methylimidazolium(dialkylimidazolium) p-toluenesulfonate, 
 1-Ethyl-3-methylimidazolium (dialkylimidazolium) diethylphosphate, 
 1-Ethyl-3-methylimidazolium (dialkylimidazolium) thiocyanate, 
 1-Ethyl-3-methylimidazolium (dialkylimidazolium) ethylsulfate, 
 1-Ethyl-3-methylimidazolium (dialkylimidazolium) trifluoroacetate, 
 1-Ethyl-3-methylimidazolium (dialkylimidazolium) trifluoromethane sulfonate, 
 1-Ethyl-3-methylimidazolium (dialkylimidazolium) tetrafluoroborate, 
 1-Butyl-2,3-dimethylimidazolium (trialkylimidazolium) trifluoromethylsulfonate, or 
 1-Propyl-3-methylimidazolium (dialkylimidazolium) iodide. 
 
     
     
       3. The method according to  claim 1 , in which the essential oil is a citrus oil and the ionic liquid is 1-ethyl-3-methylimidazolium (dialkylimidazolium) ethylsulfate. 
     
     
       4. The method according to  claim 3 , in which the citrus oil is orange oil. 
     
     
       5. The method according to  claim 1 , in which the treatment of the oil with the ionic liquid comprises mixing of the oil and the ionic liquid, allowing a layer of the oil to separate from a layer of the ionic liquid, and removing at least one of the oil layer or the ionic liquid layer. 
     
     
       6. The method according to  claim 5 , in which the treated oil is rinsed with water, and the rinsed oil layer is separated from the water. 
     
     
       7. The method according to  claim 6 , in which the rinsed oil is dried.